Inspiron 1720 - how to return to manufacturer settings?

My laptop has numerous errors & crashes etc, system restore doesn't work and diagnostics won't run, can someone please tell me how to restore to manufacturer settings before it stops turning on please?

2 As the computer starts, press <F8> on the keyboard until the Advanced Boot Options menu appears on the screen.

Note:
You must press <F8> before the Windows logo appears on the
screen. If you press <F8> after the Windows logo appears on the
screen, the Advanced Boot Options menu will not appear on the screen.
If you do not see the Advanced Boot Options menu, restart the computer,
and then repeat this step until you see the menu on the screen.

3 Press the <Down Arrow> on the keyboard to select Repair
Your Computer on the Advanced Boot Options menu, and then press
<Enter>.

4 Specify the language settings that you want, and then click Next.

5 Log in as a user who has administrative credentials, and then click OK.

2 As the computer starts, press <F8> on the keyboard until the Advanced Boot Options menu appears on the screen.

Note:
You must press <F8> before the Windows logo appears on the
screen. If you press <F8> after the Windows logo appears on the
screen, the Advanced Boot Options menu will not appear on the screen.
If you do not see the Advanced Boot Options menu, restart the computer,
and then repeat this step until you see the menu on the screen.

3 Press the <Down Arrow> on the keyboard to select Repair
Your Computer on the Advanced Boot Options menu, and then press
<Enter>.

4 Specify the language settings that you want, and then click Next.

5 Log in as a user who has administrative credentials, and then click OK.